The present application relates to a method of transferring a layer of graphene from one substrate to another substrate to allow further processing or finishing. The present disclosure also relates to a semiconductor structure and device including the transferred layer of graphene.
Several trends presently exist in the semiconductor and electronics industry including, for example, devices are being fabricated that are smaller, faster and require less power than the previous generations of devices. One reason for these trends is that personal devices such as, for example, cellular phones and personal computing devices, are being fabricated that are smaller and more portable. In addition to being smaller and more portable, personal devices also require increased memory, more computational power and speed. In view of these ongoing trends, there is an increased demand in the industry for smaller and faster transistors used to provide the core functionality of the integrated circuits used in these devices.
Accordingly, in the semiconductor industry there is a continuing trend toward fabricating integrated circuits (ICs) with higher densities. To achieve higher densities, there has been, and continues to be, efforts toward down scaling the dimensions of the devices on semiconductor wafers generally produced from bulk silicon. These trends are pushing the current technology to its limits. In order to accomplish these trends, high densities, smaller feature sizes, smaller separations between features, and more precise feature shapes are required in integrated circuits (ICs).
Significant resources go into down scaling the dimensions of devices and increasing packing densities. For example, significant time may be required to design such down scaled transistors. Moreover, the equipment necessary to produce such devices may be expensive and/or processes related to producing such devices may have to be tightly controlled and/or be operated under specific conditions. Accordingly, there are significant costs associated with exercising quality control over semiconductor fabrication.
In view of the above, the semiconductor industry is pursuing graphene to achieve some of the aforementioned goals. Graphene, which is essentially a flat sheet of carbon atoms, is a promising material for radio frequency (RF) transistors and other electronic transistors. Typical RF transistors are made from silicon or more expensive semiconductors such as, for example, indium phosphide (InP). The measured mobility of electrons in graphene was found to be as high as 200,000 cm2V−1 s−1 while it is only about 5400 cm2V−1 s−1 for InP and about 1400 cm2V−1 s−1 for silicon.
High quality graphene is typically formed on a copper foil that does not allow for easy processing using existing semiconductor device processes. As such, there is a need for a method that permits the transfer of a layer of graphene formed on a copper foil to a substrate, such as a semiconductor substrate, which can then be further processed using existing semiconductor device processing techniques.